1. Field of the Invention
The present invention relates generally to a method for making a probe device having a detective function, and more particularly to an automatic process for making the probe device by applying the microelectrodischarge machining (Micro-EDM) technology and the electrochemical discharge machining technology.
2. Description Related Art
As shown in FIG. 1, a probing device, such as a probe card 1, is used for testing the circuit function of a wafer 2. In the process of doing such testing, the probe card 1 must come in contact smoothly with the circuit of the wafer 2. The test value is then transmitted to a computer for determining the normality of function of the circuit on the wafer. The probe card 1 is formed of a printed circuit board (PCB) 3 on which the circuit is arranged for testing purpose. There are a plurality of probes 4 which are arranged in the underside of the PCB 3. The arrangement of the probes 4 is specifically designed such that the number and the layout of the probes 4 are dependent on the wafers different in circuit function.
There are two kinds of the probe cards. The first kind is an epoxy resin ring probe card. The second kind is a vertical contact probe card. The epoxy resin probe card has advantages of being suitable for use for probing a high-density wafer and for testing the multiple wafer, and disadvantages of having a smoothness which can not be easily controlled to result in the uneven exertion of application force of the probes on the wafer. The vertical contact probe card has a better probe smoothness, and a low density which is responsible for making the method for producing a probe rather complicated.
As shown in FIG. 2, the epoxy resin probe card is made by a conventional method which is time-consuming and is not cost-effective at best. The method includes the steps as follows:
1. The coordinate values of the holes to be drilled are entered into a numerically-controlled drilling system to facilitate the drilling of holes on a plastic piece.
2. The probes are manually fastened with the holes of the plastic piece.
3. The probes are secured to the holes of the plastic piece which is provided with a coating of epoxy resin.
4. The smoothness of each probe and the position of each probe are observed with the naked eye.
5. The plastic piece is baked.
6. The plastic piece is welded to a PCB board.
7. The microadjustment of the smoothness and the location of each probe is done manually.
8. The probe card is tested manually.
9. The probe card is finally produced.
It is therefore readily apparent that the conventional method described above is not cost-effective, and that the conventional method described above is not able to produce a probe card with precision in terms of the vertical smoothness of the probes and the horizontal position of the probes.